Support creating shares without email address

[PhrozenByte]

⚠️ This issue respects the following points: ⚠️

• [x] I agree to follow Nextcloud's Code of Conduct.

Describe the goal you'd like to achieve

As a poll owner, I want to be able to create shares without email address, because it allows one to realize more complex use cases that require poll owners to send invitations for single participations manually (e.g. sending one participation link to multiple individuals, or sending multiple participation links to one common email address used by multiple individuals).

Describe possible solutions

Next to listing known Nextcloud users, contacts, special formats like Name <email>, etc. the "Share with" textbox should accept arbitrary text and use that to create a single participant share without an email address, but the text entered as display name.

Additional context

Also see #3236 and #3886

[github-actions[bot]]

This issue is marked as stale, because it had no activity in the last 30 days. It will be closed in 5 days.